Enable support for C# 9.0 records (#1419)

* Enable support for C# 9.0 records

* Make unit test pass by upgrading AssertCompile's Roslyn dependency to understand C# 9.0. This requires dropping the dependency on .NET 4.52.

* Code review: rename suggested

src/NJsonSchema.CodeGeneration.CSharp.Tests/GeneralGeneratorTests.cs

@@ -1625,6 +1625,31 @@ public async Task When_record_no_setter_in_class_and_constructor_provided()
             AssertCompile(output);
         }
 
+        [Fact]
+        public async Task When_native_record_no_setter_in_class_and_constructor_provided()
+        {
+            //// Arrange
+            var schema = JsonSchema.FromType<Address>();
+            var data = schema.ToJson();
+            var generator = new CSharpGenerator(schema, new CSharpGeneratorSettings
+            {
+                ClassStyle = CSharpClassStyle.Record,
+                GenerateNativeRecords = true
+            });
+
+            //// Act
+            var output = generator.GenerateFile("Address");
+
+            //// Assert
+            Assert.Contains(@"record Address", output);
+            Assert.Contains(@"public string Street { get; init; }", output);
+            Assert.DoesNotContain(@"public string Street { get; set; }", output);
+
+            Assert.Contains("public Address(string @city, string @street)", output);
+
+            AssertCompile(output);
+        }
+
         public abstract class AbstractAddress
         {
             [JsonProperty("city")]

src/NJsonSchema.CodeGeneration.CSharp.Tests/NJsonSchema.CodeGeneration.CSharp.Tests.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netcoreapp5.0;net452</TargetFrameworks>
+    <TargetFrameworks>netcoreapp5.0</TargetFrameworks>
     <IsPackable>false</IsPackable>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <NoWarn>1998,1591</NoWarn>
@@ -38,7 +38,7 @@
     <PackageReference Include="xunit" Version="2.3.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.3.1" />
 
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.8.0" Condition="'$(TargetFramework)' == 'netcoreapp5.0'" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.11.0" Condition="'$(TargetFramework)' == 'netcoreapp5.0'" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="1.3.2" Condition="'$(TargetFramework)' == 'net452'" />
 
     <DotNetCliToolReference Include="dotnet-xunit" Version="2.3.1" />

src/NJsonSchema.CodeGeneration.CSharp/CSharpGeneratorSettings.cs

@@ -144,5 +144,8 @@ public CSharpGeneratorSettings()
 
         /// <summary>Gets or sets a value indicating whether to generate Nullable Reference Type annotations (default: false).</summary>
         public bool GenerateNullableReferenceTypes { get; set; }
+
+        /// <summary>Generate C# 9.0 record types instead of record-like classes.</summary>
+        public bool GenerateNativeRecords { get; set; }
     }
 }

src/NJsonSchema.CodeGeneration.CSharp/Models/ClassTemplateModel.cs

@@ -102,6 +102,9 @@ public ClassTemplateModel(string typeName, CSharpGeneratorSettings settings,
         /// <summary>Gets a value indicating whether the class style is Record.</summary>
         public bool RenderRecord => _settings.ClassStyle == CSharpClassStyle.Record;
 
+        /// <summary>Gets a value indicating whether to generate records as C# 9.0 records.</summary>
+        public bool GenerateNativeRecords => _settings.GenerateNativeRecords;
+
         /// <summary>Gets a value indicating whether to render ToJson() and FromJson() methods.</summary>
         public bool GenerateJsonMethods => _settings.GenerateJsonMethods;
 

src/NJsonSchema.CodeGeneration.CSharp/Templates/Class.liquid

@@ -25,7 +25,7 @@
 [System.Obsolete{% if HasDeprecatedMessage %}({{ DeprecatedMessage | literal }}){% endif %}]
 {% endif -%}
 {% template Class.Annotations %}
-{{ TypeAccessModifier }} {% if IsAbstract %}abstract {% endif %}partial class {{ClassName}} {% template Class.Inheritance %}
+{{ TypeAccessModifier }} {% if IsAbstract %}abstract {% endif %}partial {% if GenerateNativeRecords %}record{% else %}class{% endif %} {{ClassName}} {% template Class.Inheritance %}
 {
 {% if IsTuple -%}
     public {{ ClassName }}({% for tupleType in TupleTypes -%}{{ tupleType }} item{{ forloop.index }}{% if forloop.last == false %}, {% endif %}{% endfor -%}) : base({% for tupleType in TupleTypes -%}item{{ forloop.index }}{% if forloop.last == false %}, {% endif %}{% endfor -%})
@@ -92,7 +92,7 @@
     [System.Obsolete{% if property.HasDeprecatedMessage %}({{ property.DeprecatedMessage | literal }}){% endif %}]
 {%   endif -%}
     {% template Class.Property.Annotations %}
-    public {{ property.Type }} {{ property.PropertyName }}{% if RenderInpc == false and RenderPrism == false %} { get; {% if property.HasSetter and RenderRecord == false %}set; {% endif %}}{% if property.HasDefaultValue and RenderRecord == false %} = {{ property.DefaultValue }};{% elsif GenerateNullableReferenceTypes and RenderRecord == false -%} = default!;{% endif %}
+    public {{ property.Type }} {{ property.PropertyName }}{% if RenderInpc == false and RenderPrism == false %} { get; {% if property.HasSetter and RenderRecord == false %}set; {% elsif RenderRecord and GenerateNativeRecords %}init; {% endif %}}{% if property.HasDefaultValue and RenderRecord == false %} = {{ property.DefaultValue }};{% elsif GenerateNullableReferenceTypes and RenderRecord == false -%} = default!;{% endif %}
 {% else %}
     {
         get { return {{ property.FieldName }}; }